[PATCH] arm: enable unaligned accesses by default if EFI is configured
Ilias Apalodimas
ilias.apalodimas at linaro.org
Fri Mar 17 14:42:57 CET 2023
Heinrich reports that compiling with LTO & EFI breaks armv7 and arm11*
builds. The reason is that LTO (maybe a binutils bug?) replaces the
asm version of allow_unaligned() with the __weak definition of the
function. As a result EFI code ends up running with unaligned accesses
disabled and eventually crashes.
So let's enable unaligned access for those architectures during
our start.S routines and avoid the linker issues.
Reported-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
arch/arm/cpu/arm11/Makefile | 4 ----
arch/arm/cpu/arm11/sctlr.S | 25 -------------------------
arch/arm/cpu/arm1136/start.S | 3 +++
arch/arm/cpu/arm1176/start.S | 3 +++
arch/arm/cpu/armv7/Makefile | 1 -
arch/arm/cpu/armv7/sctlr.S | 22 ----------------------
arch/arm/cpu/armv7/start.S | 3 +++
include/asm-generic/unaligned.h | 4 ----
lib/efi_loader/efi_device_path.c | 7 -------
lib/efi_loader/efi_setup.c | 12 ------------
10 files changed, 9 insertions(+), 75 deletions(-)
delete mode 100644 arch/arm/cpu/arm11/sctlr.S
delete mode 100644 arch/arm/cpu/armv7/sctlr.S
diff --git a/arch/arm/cpu/arm11/Makefile b/arch/arm/cpu/arm11/Makefile
index 5dfa01ae8d05..5d721fce12b5 100644
--- a/arch/arm/cpu/arm11/Makefile
+++ b/arch/arm/cpu/arm11/Makefile
@@ -4,7 +4,3 @@
# Wolfgang Denk, DENX Software Engineering, wd at denx.de.
obj-y = cpu.o
-
-ifneq ($(CONFIG_SPL_BUILD),y)
-obj-$(CONFIG_EFI_LOADER) += sctlr.o
-endif
diff --git a/arch/arm/cpu/arm11/sctlr.S b/arch/arm/cpu/arm11/sctlr.S
deleted file mode 100644
index 74a7fc4a25b6..000000000000
--- a/arch/arm/cpu/arm11/sctlr.S
+++ /dev/null
@@ -1,25 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0+ */
-/*
- * Routines to access the system control register
- *
- * Copyright (c) 2019 Heinrich Schuchardt
- */
-
-#include <linux/linkage.h>
-
-/*
- * void allow_unaligned(void) - allow unaligned access
- *
- * This routine sets the enable unaligned data support flag and clears the
- * aligned flag in the system control register.
- * After calling this routine unaligned access does no longer leads to a
- * data abort or undefined behavior but is handled by the CPU.
- * For details see the "ARM Architecture Reference Manual" for ARMv6.
- */
-ENTRY(allow_unaligned)
- mrc p15, 0, r0, c1, c0, 0 @ load system control register
- orr r0, r0, #1 << 22 @ set unaligned data support flag
- bic r0, r0, #2 @ clear aligned flag
- mcr p15, 0, r0, c1, c0, 0 @ write system control register
- bx lr @ return
-ENDPROC(allow_unaligned)
diff --git a/arch/arm/cpu/arm1136/start.S b/arch/arm/cpu/arm1136/start.S
index 4bc27f637366..f2a18d8f3423 100644
--- a/arch/arm/cpu/arm1136/start.S
+++ b/arch/arm/cpu/arm1136/start.S
@@ -77,7 +77,10 @@ cpu_init_crit:
mrc p15, 0, r0, c1, c0, 0
bic r0, r0, #0x00002300 @ clear bits 13, 9:8 (--V- --RS)
bic r0, r0, #0x00000087 @ clear bits 7, 2:0 (B--- -CAM)
+#if !CONFIG_IS_ENABLED(EFI_LOADER)
+ /* allow unaligned accesses since EFI requires it */
orr r0, r0, #0x00000002 @ set bit 1 (A) Align
+#endif
orr r0, r0, #0x00001000 @ set bit 12 (I) I-Cache
mcr p15, 0, r0, c1, c0, 0
diff --git a/arch/arm/cpu/arm1176/start.S b/arch/arm/cpu/arm1176/start.S
index 78a9cc173a39..0c80160702ba 100644
--- a/arch/arm/cpu/arm1176/start.S
+++ b/arch/arm/cpu/arm1176/start.S
@@ -79,7 +79,10 @@ cpu_init_crit:
mrc p15, 0, r0, c1, c0, 0
bic r0, r0, #0x00002300 @ clear bits 13, 9:8 (--V- --RS)
bic r0, r0, #0x00000087 @ clear bits 7, 2:0 (B--- -CAM)
+#if !CONFIG_IS_ENABLED(EFI_LOADER)
+ /* allow unailgned accesses since EFI requires it */
orr r0, r0, #0x00000002 @ set bit 1 (A) Align
+#endif
orr r0, r0, #0x00001000 @ set bit 12 (I) I-Cache
/* Prepare to disable the MMU */
diff --git a/arch/arm/cpu/armv7/Makefile b/arch/arm/cpu/armv7/Makefile
index 653eef8ad79e..ca50f6e93e10 100644
--- a/arch/arm/cpu/armv7/Makefile
+++ b/arch/arm/cpu/armv7/Makefile
@@ -13,7 +13,6 @@ obj-y += syslib.o
obj-$(CONFIG_SYS_ARM_MPU) += mpu_v7r.o
ifneq ($(CONFIG_SPL_BUILD),y)
-obj-$(CONFIG_EFI_LOADER) += sctlr.o
obj-$(CONFIG_ARMV7_NONSEC) += exception_level.o
endif
diff --git a/arch/arm/cpu/armv7/sctlr.S b/arch/arm/cpu/armv7/sctlr.S
deleted file mode 100644
index bd56e41afe18..000000000000
--- a/arch/arm/cpu/armv7/sctlr.S
+++ /dev/null
@@ -1,22 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0+ */
-/*
- * Routines to access the system control register
- *
- * Copyright (c) 2018 Heinrich Schuchardt
- */
-
-#include <linux/linkage.h>
-
-/*
- * void allow_unaligned(void) - allow unaligned access
- *
- * This routine clears the aligned flag in the system control register.
- * After calling this routine unaligned access does no longer lead to a
- * data abort but is handled by the CPU.
- */
-ENTRY(allow_unaligned)
- mrc p15, 0, r0, c1, c0, 0 @ load system control register
- bic r0, r0, #2 @ clear aligned flag
- mcr p15, 0, r0, c1, c0, 0 @ write system control register
- bx lr @ return
-ENDPROC(allow_unaligned)
diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
index 7d7aac021e22..abb89efb9ed5 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -197,7 +197,10 @@ ENTRY(cpu_init_cp15)
mrc p15, 0, r0, c1, c0, 0
bic r0, r0, #0x00002000 @ clear bits 13 (--V-)
bic r0, r0, #0x00000007 @ clear bits 2:0 (-CAM)
+#if !CONFIG_IS_ENABLED(EFI_LOADER)
+ /* allow unaligned accesses since EFI requires it */
orr r0, r0, #0x00000002 @ set bit 1 (--A-) Align
+#endif
orr r0, r0, #0x00000800 @ set bit 11 (Z---) BTB
#if CONFIG_IS_ENABLED(SYS_ICACHE_OFF)
bic r0, r0, #0x00001000 @ clear bit 12 (I) I-cache
diff --git a/include/asm-generic/unaligned.h b/include/asm-generic/unaligned.h
index 3d33a5a063e8..cf032ce1d4cc 100644
--- a/include/asm-generic/unaligned.h
+++ b/include/asm-generic/unaligned.h
@@ -19,8 +19,4 @@
#else
#error invalid endian
#endif
-
-/* Allow unaligned memory access */
-void allow_unaligned(void);
-
#endif
diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
index 3b267b713e98..bbaaf626d9cb 100644
--- a/lib/efi_loader/efi_device_path.c
+++ b/lib/efi_loader/efi_device_path.c
@@ -954,13 +954,6 @@ static void path_to_uefi(void *uefi, const char *src)
{
u16 *pos = uefi;
- /*
- * efi_set_bootdev() calls this routine indirectly before the UEFI
- * subsystem is initialized. So we cannot assume unaligned access to be
- * enabled.
- */
- allow_unaligned();
-
while (*src) {
s32 code = utf8_get(&src);
diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
index 58d4e1340233..bd17db61c697 100644
--- a/lib/efi_loader/efi_setup.c
+++ b/lib/efi_loader/efi_setup.c
@@ -17,15 +17,6 @@
efi_status_t efi_obj_list_initialized = OBJ_LIST_NOT_INITIALIZED;
-/*
- * Allow unaligned memory access.
- *
- * This routine is overridden by architectures providing this feature.
- */
-void __weak allow_unaligned(void)
-{
-}
-
/**
* efi_init_platform_lang() - define supported languages
*
@@ -191,9 +182,6 @@ int efi_init_early(void)
{
efi_status_t ret;
- /* Allow unaligned memory access */
- allow_unaligned();
-
/* Initialize root node */
ret = efi_root_node_register();
if (ret != EFI_SUCCESS)
--
2.39.2
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